Fwd: Basic IAQ Metrics: What You Need to Know
Mansel A NelsonProgram CoordinatorTribal Environmental Education Outreach928-523-1275
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Indoor Air Quality Tools for Schools Program
“A proactive IAQ management program is essential in preventing problems from arising in the first place.”
– Rich Prill, Building Science & IEQ Specialist, Washington State University Extension Energy Program
Dear School Leader,
Building occupants will often associate their health symptoms with exposure to indoor pollutants due to the amount of time they spend indoors, which is why it is essential to be proactive when it comes to indoor air quality. You can easily assess if your school has indoor air problems by identifying potential sources of indoor air pollution, looking for signs of ventilation problems and measuring pollutant levels. The IAQ Tools for Schools suite of materials and guidance, such as the ventilation and walkthrough inspection checklists within the IAQ Tools for Schools Action Kit, can help you with your IAQ assessment and to pinpoint potential problems in your school.
In addition to the recommendations provided in the checklists and Action Kit, tips on IAQ measurements, tests and instruments are listed below.
Carbon Dioxide (CO2) – Measuring CO2 in occupied buildings is easy to do, as the instruments are reasonably priced and the results on fresh air ventilation rates can be easily interpreted. When CO2 builds up due to inadequate air exchange, so does everything else. There is no single “magic” number for a CO2 value in a particular classroom. Good practice dictates that you control pollutant sources to the extent possible and ventilate based on the needs of the space. However, if the CO2 concentration in an occupied classroom is below 800 to 1,000 parts-per-million (ppm), that classroom is generally considered to be well-ventilated. If ambient CO2 levels (i.e., levels measured in the middle of the room with no one breathing on the meter) exceed 1,000 ppm, additional outside air ventilation may be necessary. Consult the IAQ Tools for Schools Action Kit for more information on practical and meaningful CO2 measurements.
Particle Meters – Many IAQ professionals use particle counts to compare airborne particulates of inside and outside air and to compare particulate concentrations from room-to-room. These counts are also used to evaluate incoming air delivered to the zones from heating, ventilation and air-conditioning (HVAC) systems for the purpose of judging filter effectiveness and/or investigating potential pollution sources. Two common types of particle meters are used in schools, and both have internal pumps to draw in user-defined volumes of air. One type of meter counts the particles in six ranges, such as: 0.3, 0.5, 1.0, 3.0, 5.0 and 10.0 micrometers, and displays the results in number of particles for each size range per volume of air collected. The other type of particle meter collects and displays the measurement results in particles by weight in units of micrograms per cubic meter (µg/m3). Particle meters are also useful for problem diagnostics and inspections to help identify sources of particle exposure, and to verify reductions have been achieved from interventions and mitigation efforts. Learn more about potential pollutant sources and HVAC systems in schools.
Moisture Meters – There are two basic types of moisture-sensing devices. The first uses two surface contact pads to measure moisture levels on surfaces as well as in a substrate, and the second incorporates two sharp-pointed pins that penetrate into materials to measure the percent of moisture content, or relative moisture content, on a 0 – 100 scale. This scale provides a point of reference when determining if moisture level is too high. For example, drywall and wood/paper-based products measuring over 18 percent moisture content are very likely to support mold growth. Moisture meters are handy for finding hidden moisture problems and for determining if a material is wet enough to support mold growth. Learn more about mold remediation in schools.
Remember, when it comes to measuring indoor air pollutants, it is important to understand that it is technically possible to measure far too many substances compared with the current ability to set a limit on their exposure. When you add this to the complex mixture of substances that are found in buildings, you can appreciate our mantra: “only measure what you can reasonably interpret.”
Rich Prill (Building Science and IEQ Specialist, Washington State University, Extension Energy Program) and David Blake (Environmental Specialist, Northwest Clean Air Agency)
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If you have any questions about the IAQ Tools for Schools guidance, please contact the IAQ Tools for Schools Connector Coordinator at IAQTfSConnector@....
The IAQ Tools for Schools guidance is a comprehensive resource designed to help schools maintain a healthy environment in school buildings by identifying, correcting and preventing IAQ problems. Learn more about the IAQ Tools for Schools guidance at http://www.epa.gov/iaq/schools.
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